It's absolutely insane that there's no way in HTML to associate a caption with an image. Title attributes don't count, you only see them on mouse-over, so they end up being a ‘mystery meat caption’. The closest you can get right now is putting the image in a table, and then using the table's <caption> element to caption it. Semantically, that's Just Wrong.

The <object> tag doesn't help in this regard either.

And, of course, this is never going to get fixed for the mainstream web, because HTML4 is no longer being updated, XHMTL1 is just a transition, and the w3c is going off into their weird fantasy-land for XHTML2.